POSSIBLE RELATIONSHIPS AMONG SOUTH CHINA SEA SSTA, SOIL MOISTURE ANOMALIES IN SOUTHWEST CHINA AND SUMMER PRECIPITATION IN EASTERN CHINA

By using 1958-2001 NOAA extended reconstructed sea surface temperature (SST) data, ERA40 reanalysis soil moisture data and precipitation data of 444 stations in China (east of 100°E), the possible relationships among South China Sea (SCS) SST anomaly (SSTA), soil moisture anomalies (SMA) and summer precipitation in eastern China as well as their possible physical processes are investigated. Results show that the SSTA of SCS bears an evidently negative correlation with spring soil moisture in the east part of Southwest China. More (less) precipitation happens in the Yangtze River basin and less (more) in the Southeast China in summer when the SSTA of SCS is higher (lower) than normal and the soil in the east part of Southwest China is dry (wet) in spring. Further analysis shows that when the SSTA of SCS is high (low), the southwesterly wind at low level is weak (strong), decreasing (increasing) the water vapor transport in South China, resulting in reduced (increased) spring precipitation in the east part of Southwest China and more (less) soil moisture in spring. Through the evaporation feedback mechanism, the dry (wet) soil makes the surface temperature higher (lower) in summer, causing the westward extension (eastward retreat) of the West Pacific Subtropical High, eventually leading to the summer precipitation anomalies.